Abstract: A music accompaniment machine processes a music accompaniment file to alter a stored beat of the music accompaniment file to match a beat established by a user. The machine identifies the beat of the user using a voice analyzer. The voice analyzer isolates the user's singing signal from excess background noise and appends segment position information to the singing signal, which is indicative of the beat established by the singer. A MIDI controller alters the musical beat of the music accompaniment file so that it matches the beat established by the user.

Abstract: A real time dynamic MIDI controller pre-processes MIDI files to facilitate playback by re-formatting stored MIDI files into a modified MIDI file format and simultaneously eliminating MIDI META events that are stored in the file, but unnecessary for playback. The MIDI controller includes an administrator to effect channel grouping, channel voice message grouping, or a combination thereof, to facilitate the control of selected MIDI file parameters. The real time dynamic MIDI controller also includes an output interface circuit to coordinate the transmission of one or more MIDI file that the MIDI controller has processed.

Abstract: A reverberation network for processing an audio signal including a plurality of wave-ladder filters, each of which simulates a corresponding reflected audio signal from wave propagation in a selected direction, wherein each of the plurality of wave-ladder filters receives as input a signal derived from the audio signal; and an adder which combines the corresponding reflected signals of the plurality of wave-ladder filters to produce a reverberation signal.